The overall aim of this project is to develop transgenic rat models for hypertension research with specific inhibition of gene expression. This will allow us to define the function of single genes in specific cell types and to unravel the complex interactions of blood pressure regulating mechanisms. These techniques, once established with the key genes of the renin angiotensin system, will in principle be applicable universally to any other gene. The new transgenic rat models can be expected to be of value for pathophysiologic and therapeutic research. Specifically we want to develop the methodology of enzymatic cleavage of the target mRNA by the use of synthetic catalytic RNA sequences (ribozymes) which are included within an antisense RNA construct. This will potentially result in the destruction of the target mRNA and complete inhibition of a single gene. We plan to work with the two key genes of the renin angiotensin system (RAS), renin and angiotensinogen, which complement each other with respect to already available materials, functional analysis in transgenic rats and previous experience. Experiments with both genes will be conducted in 4 steps: 1. Synthesis of appropriate renin and angiotensinogen ribozyme constructs. 2. Testing of the inhibitory constructs in vitro. 3. Testing of the constructs in cell culture. 4. Constructs which appear suitable from the in vitro and cell culture results and which inhibit or cleave Ren-2 or angiotensinogen mRNA specifically will be used to inhibit renin or angiotensinogen expression in transgenic rats. In the future the use of inducible promoters may allow us to study 'on' and 'off' effects of the constructs and provide the unprecedented possibility of relating quantitatively gene activity to the phenotype e.g. blood pressure and hormone levels. In Summary our projects aim to develop a universally applicable methodology for new, more specific rat models for hypertension research using the RAS as a paradigm, to unravel the molecular, cellular and systemic functions of renin and angiotensinogen, to identify the relative contribution of the local tissue RAS versus the hormonal plasma RAS and their complex interactions and to provide these new transgenic rat models deficient in the expression of specific genes to the scientific community for new developments in pathophysiological and therapeutic research and possibly including somatic gene substitution experiments.